1. Field of the Invention
The present invention relates generally to an apparatus and a method for capturing images, and more particularly to an apparatus and a method for capturing images by applying different color filters to two pixel regions with IR blocking filters removed so that optical signals in the visible band and IR signals can be received.
2. Description of the Prior Art
Recently, an increasing number of devices, such as phones, are equipped with cameras.
Cameras generally include lenses and image sensors. Lenses collect light reflected by objects, and image sensors detect light collected by lenses and convert them into digital image signals. Image sensors are classified into image pickup tubes and solid image sensors, typical examples of which include CCDs (Charged Coupled Devices) and CMOSs (Complementary Metal Oxide Semiconductors).
In order to increase the resolution of images captured with cameras, it is customary to decrease the unit area of each pixel within the sensing region while maintaining the total area of the sensing region. Particularly, a decrease in unit area of pixels leads to an increase in the number of pixels in the sensing region, which means that high-resolution images are obtained. However, this approach has a problem in that, although high-resolution images may be obtained, high-sensitivity images are hard to obtain. This is because a decrease in the unit area of pixels results in reduction in the amount of light reaching respective pixels.
Therefore, stacked image sensors have been developed so that all major visible light signals, e.g. red; green, and blue signals (hereinafter, abbreviated as R, G, B signals) can be extracted from a single pixel region while the pixel size remains the same. These image sensors are based on the principle that, when light is absorbed by a silicon layer of the sensors, the depth of absorption varies depending on the wavelength of light. As a result, R, G, B signals are detected at different depths of the silicon layer. However, this type of image sensor has a problem in that, although the resolution of images may be improved because all the R, G, B signals can be obtained from a single pixel, the color reproduction characteristics are degraded because it is difficult to accurately differentiate R, G, B signals from the silicon layer. In other words, it is difficult to obtain high-quality images.
Consequently, it is necessary to provide means to improve the color reproduction performance while reducing degradation in the resolution of the images.